cameraif.available() always returns True

[cursor]

What is wrong

cameraif.available() is exported as a capability probe, but the implementation is a constant:

static mp_obj_t cameraif_available(void) {
    return mp_const_true;
}

A probe that cannot fail is not a probe. Code that branches on available() before constructing a Camera will always take the camera path, including on firmware built without a sensor driver or on a board with no CSI.

What it should mean

Either:

• return whether this firmware was built with at least one CONFIG_CAMERA_* driver linked and the CSI controller is present, or
• be removed from the public surface until it can tell the truth.

Why it surfaced

The examples catalog work needed a honest "does this board have a camera?" check. board_config.camera already raises usefully; available() does not add anything until it can fail.